Foaming light diffusion plate and preparation method and application thereof

Abstract

The invention provides a foaming light diffusion plate and a preparation method and application thereof, and particularly relates to the technical field of light diffusion plates. The foaming light diffusion plate comprises an upper layer, a middle layer and a lower layer which are arranged in a stacked mode, and every two adjacent layers are different in structure. The upper layer is provided with a large foam structure, a small foam structure or a solid structure; the middle layer is provided with a large foam hole structure and / or a small foam hole structure; and the lower layer has a large foam structure, a small foam structure or a solid structure. According to the foaming light diffusion plate, a differentially designed foam system is introduced into a three-layer structure, so that optical performance matching of high light transmittance, high haze and high brightness uniformity is realized. Large bubbles are used as light channels to reduce light scattering loss so as to improve the light transmittance, and meanwhile, small bubbles are used for enhancing the light scattering capacity so as to improve the haze and the light uniformizing effect. According to the invention, the density is as low as 0.70-0.85 g / cm < 3 >, the lightweight effect is obvious, the uniformity is greater than or equal to 84.2%, the material has good mechanical properties and heat resistance, and the material cost and the transportation energy consumption are reduced.

Description

Technical Field

[0001] This invention relates to the field of light diffusion plate technology, and in particular to a foamed light diffusion plate, its preparation method, and its application. Background Technology

[0002] Foamed light diffusers, as a key optical functional material, have been widely used in various fields such as LED lighting, LCD backlight modules, architectural lighting, automotive interior lighting, and medical equipment. Their core function is to achieve multiple scattering of incident light through their internal microstructure, thereby achieving a uniform light distribution and providing a soft, glare-free visual effect. Simultaneously, because the foamed structure significantly reduces material density, these sheets maintain good mechanical properties while offering lightweight advantages, making them particularly suitable for large-size display devices and weight-sensitive applications.

[0003] Most mainstream foamed light diffusers on the market currently use general-purpose plastics such as polystyrene (PS) as the base material, forming a uniform, fine closed-cell structure in the middle layer of the board through physical or chemical foaming processes. These micron-sized pores, as the main light scattering centers, can effectively improve the material's haze, achieving good shading and light uniformity. However, this single-scale pore structure has a significant performance bottleneck: excessively high pore density or excessively small pore size, while helping to improve haze, will cause light to undergo too many scattering paths within the material, resulting in significant light energy loss and thus significantly reducing transmittance. Therefore, traditional foamed diffusers often struggle to simultaneously achieve the mutually restrictive optical properties of high haze and high transmittance.

[0004] Furthermore, as display technology advances towards higher brightness, thinner profiles, and larger sizes, higher overall performance requirements are being placed on light diffusion plates. Single-cell structures not only lack flexibility in optical control but also have limitations in mechanical properties. For example, over-foaming can lead to increased brittleness and decreased impact resistance, affecting processing and service life. At the same time, higher raw material consumption (such as resin matrix and light diffusing agents) also brings cost pressures.

[0005] In recent years, bimodal cell structures have attracted attention due to their potential for synergistically optimizing the multifunctionality of materials. Despite their promising applications, precisely controlling the size, density, and spatial distribution of cells in different layers under continuous industrial production conditions remains a significant challenge. Currently, there is a lack of effective methods to stably prepare light diffusion plates with specific cell configurations (such as differentiated cell structures between upper and lower layers and the core layer) and excellent optical, mechanical, and low-density characteristics through synergistic control of the formulation system and process parameters during co-extrusion. Especially in multilayer co-extrusion systems, the complex coupling relationships between melt rheological behavior, foaming kinetics, and interfacial compatibility of each layer further increase the difficulty of achieving controllable bimodal foaming.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a foamed light diffuser plate, its preparation method and application, aiming to solve at least one of the above-mentioned technical problems in the prior art.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: A first aspect of the present invention provides a foamed light diffuser plate, comprising an upper layer, a middle layer, and a lower layer stacked together, wherein adjacent layers have different structures; the upper layer has a large-pore structure, a small-pore structure, or a solid structure; the middle layer has a large-pore structure and / or a small-pore structure; the lower layer has a large-pore structure, a small-pore structure, or a solid structure. The upper layer and the lower layer cannot both be solid structures simultaneously.

[0009] Furthermore, the major axis of the large pore structure is 150~350μm, the minor axis is 50~100μm, and the ratio of the major axis to the minor axis is 2.0~10.0.

[0010] Preferably, the major axis of the micropore structure is 5~50μm, the minor axis is 5~50μm, and the ratio of the major axis to the minor axis is 1.0~3.0.

[0011] Preferably, the cell density of the foamed light diffuser plate is 500~2000 cells / cm³. 2 .

[0012] Furthermore, the thickness of the foamed light diffuser plate is 0.8~3.0mm.

[0013] Furthermore, the thickness ratio of the upper layer, the middle layer, and the lower layer is 1:(0.25~15):1.

[0014] When the intermediate layer has a large pore structure, the thickness ratio of the upper layer, the intermediate layer and the lower layer is 1:(6~10):1.

[0015] Preferably, when the intermediate layer has a small pore structure, the thickness ratio of the upper layer, the intermediate layer, and the lower layer is 1:(0.5~4):1. Further, the upper layer has a large pore structure or a small pore structure, and the lower layer has a large pore structure or a small pore structure.

[0016] The second aspect of the present invention provides a method for preparing the foamed light diffuser plate, comprising the following steps: co-extruding a three-layer structure by co-extrusion, and then drawing and cooling to form the foamed light diffuser plate.

[0017] Further, by weight, the formulation of the upper layer and / or the lower layer includes 80-90 parts of the first substrate resin, 0.1-1.0 parts of the light diffusing agent, 0.05-0.5 parts of the nucleating agent, 0-1.0 parts of the foaming agent, 2-5 parts of the toughening agent, 1-3 parts of the compatibilizer, 0.1-0.5 parts of the antioxidant, and 0.1-0.5 parts of the ultraviolet absorber.

[0018] Preferably, the intermediate layer formulation comprises, by weight, 80-90 parts of the second substrate resin, 0-1.0 parts of light diffusing agent, 0.05-0.5 parts of nucleating agent, 0.4-1.0 parts of foaming agent, 2-5 parts of toughening agent, 1-3 parts of compatibilizer, 0.1-0.5 parts of antioxidant, and 0.1-0.5 parts of ultraviolet absorber.

[0019] Preferably, the materials of the first substrate resin and / or the second substrate resin are each independently PMMA, PC or PS.

[0020] Furthermore, the difference in melt flow index between the first substrate resin and the second substrate resin is ≤8.

[0021] Alternatively, when the upper layer and / or the lower layer has a small pore structure, the melt index of the first substrate resin is greater than the melt index of the second substrate resin.

[0022] Alternatively, when the upper layer and / or the lower layer has a large pore structure, the melt index of the first substrate resin is less than the melt index of the second substrate resin.

[0023] Furthermore, the light diffusing agent includes organosilicon-based light diffusing agents.

[0024] Preferably, the nucleating agent comprises silane-modified silicon dioxide.

[0025] Preferably, the silane-modified silica includes at least one of dodecyltrimethoxysilane-modified SiO2 (DTMS-SiO2), hexadecyltrimethoxysilane-modified SiO2 (HDTMS-SiO2), octadecyltrimethoxysilane-modified SiO2 (OTS-SiO2), polydimethylsiloxane-modified SiO2 (PDMS-SiO2), and polymethylsilsesquioxane-modified SiO2 (PMSQ-SiO2).

[0026] Preferably, the foaming agent has a gas generation capacity of 30~80mL / g.

[0027] Preferably, the difference between the gas generation of the blowing agent used to form a large pore structure and the gas generation of the blowing agent used to form a small pore structure is >20 mL / g.

[0028] Preferably, the toughening agent comprises at least one of high-impact polystyrene (HIPS), hydrogenated styrene-butadiene block copolymer (SEBS), styrene-butadiene-styrene block copolymer (SBS), and methyl methacrylate-butadiene-styrene terpolymer (MBS).

[0029] Preferably, the compatibilizer is selected from at least one of St-MMA block copolymer, maleic anhydride grafted polystyrene (PS-g-MAH), PS-SMA, SBS-g-MAH, MBS-g-MAH, and glycidyl methacrylate modified PS (PS-g-GMA).

[0030] Preferably, the antioxidant is selected from phenolic antioxidants, phosphite antioxidants, phosphorus antioxidants, or phenol-phosphorus complex antioxidants.

[0031] Preferably, the grades of the phenolic antioxidants include 1010 or 1076.

[0032] Preferably, the grade of the phosphite antioxidant includes 168.

[0033] Preferably, the grades of the phenol-phosphorus composite antioxidant include at least one of B-1, B-2, and B-3.

[0034] Preferably, the ultraviolet absorber is selected from benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, or triazine-based ultraviolet absorbers.

[0035] Preferably, the grades of the benzophenone-based ultraviolet absorbers include UV-9 and UV-531.

[0036] Preferably, the grades of the benzotriazole UV absorbers include UV-P and UV-327.

[0037] Preferably, the triazine UV absorber is designated as UV-1164.

[0038] Preferably, the formulation further includes a hindered amine light stabilizer.

[0039] Preferably, the hindered amine light stabilizer is a grade including at least one of 770, 944, 5050H or 622.

[0040] Furthermore, the co-extrusion process parameters are as follows: the temperature of each zone of the extruder is 160~280℃, the lip temperature is 210~290℃, the front, middle and rear roller temperatures are 70~130℃, and the traction speed is 2.5~3.5m / min; Alternatively, PC resin can be used as the base material, with an extrusion temperature of 200~280℃ and a lip temperature of 250~290℃.

[0041] A third aspect of the present invention provides the application of the aforementioned foamed light diffuser plate in a liquid crystal display.

[0042] Compared with the prior art, the present invention has at least the following beneficial effects: The foamed light diffuser plate provided by this invention achieves a synergistic combination of high light transmittance, high haze, and high brightness uniformity by introducing a differentiated pore system into its three-layer structure. Large pores are used as light channels to reduce light scattering loss and improve transmittance, while small pores enhance light scattering capabilities to improve haze and light uniformity. This effectively overcomes the technical bottleneck of traditional foamed diffuser plates where transmittance and haze are difficult to balance. The resulting foamed light diffuser plate has a density as low as 0.70~0.85 g / cm³. 3 It exhibits significant lightweighting effects, with a uniformity of ≥84.2%, while also possessing excellent mechanical properties and heat resistance, thus reducing material costs and transportation energy consumption.

[0043] The preparation method provided by this invention, through a multi-layer co-extrusion process combined with formulation and process control, achieves stable and continuous preparation of bimodal bubble structures in light diffusion plates. This enables precise control of optical properties, not only improving production efficiency and process tolerance but also ensuring batch-to-batch stability, making it suitable for large-scale industrial production.

[0044] The application provided by this invention, given the advantages of the aforementioned foamed light diffusion plate, significantly reduces the overall weight of large-size display terminals due to its lightweight characteristics, which is beneficial for transportation and installation and reduces structural support costs; it also promotes the upgrading of downstream products towards high performance, energy saving and cost reduction, and thinness. Attached Figure Description

[0045] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of the structure of the foamed light diffuser plate provided in Example 1; Figure 2 This is a schematic diagram of the structure of the foamed light diffuser plate provided in Example 7; Figure 3 This is a schematic diagram of the structure of the foamed light diffuser plate provided in Example 8. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0048] In the following, the terms “comprising,” “having,” and their cognates, which may be used in various embodiments of the invention, are intended only to indicate a particular feature, number, step, operation, element, component, or combination thereof, and should not be construed as excluding, firstly, the presence of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, or adding the possibility of one or more features, numbers, steps, operations, elements, components, or combinations thereof.

[0049] A first aspect of the present invention provides a foamed light diffuser plate, comprising an upper layer, a middle layer, and a lower layer stacked together, wherein adjacent layers have different structures; the upper layer has a large-pore structure, a small-pore structure, or a solid structure; the middle layer has a large-pore structure and / or a small-pore structure; the lower layer has a large-pore structure, a small-pore structure, or a solid structure. The upper layer and the lower layer cannot both be solid structures simultaneously.

[0050] The foamed light diffuser plate provided by this invention achieves a synergistic combination of high light transmittance, high haze, and high brightness uniformity by introducing a differentiated pore system into its three-layer structure. Large pores are used as light channels to reduce light scattering loss and improve transmittance, while small pores enhance light scattering capabilities to improve haze and light uniformity. This effectively overcomes the technical bottleneck of traditional foamed diffuser plates where transmittance and haze are difficult to balance. The resulting foamed light diffuser plate has a density as low as 0.70~0.85 g / cm³. 3It exhibits significant lightweighting effects, with a uniformity of ≥84.2%, while also possessing excellent mechanical properties and heat resistance, thus reducing material costs and transportation energy consumption.

[0051] It should be noted that the intermediate layer can simultaneously possess both large and small pore structures, forming a bimodal pore structure. This allows for the synergistic optical control of both pore sizes: the large pores act as light channels, effectively reducing scattering loss during light propagation and thus improving transmittance; while the small pores act as efficient light scattering centers, enhancing multi-directional light scattering capabilities, significantly improving haze and brightness uniformity, and mitigating display defects such as shadows and bright lines. This structure achieves a good balance between high transmittance and high haze, overcoming the technical bottleneck of traditional single-pore structures that struggle to balance both. It also helps reduce board density, achieving lightweighting, and improves the stability and tolerance of the foaming process.

[0052] Furthermore, the major axis of the large pore structure is 150~350μm, the minor axis is 50~100μm, and the ratio of the major axis to the minor axis is 2.0~10.0.

[0053] Typically, but not limitingly, the major axis of the large pore structure can be, for example, 150 μm, 180 μm, 200 μm, 220 μm, 250 μm, 280 μm, 300 μm, 320 μm, or 350 μm, or any value within the range of 150 to 350 μm; the minor axis can be, for example, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or 100 μm, or any value within the range of 50 to 100 μm; the ratio of the major axis to the minor axis can be, for example, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, or 10.0, or any value within the range of 2.0 to 10.0.

[0054] Preferably, the major axis of the micropore structure is 5~50μm, the minor axis is 5~50μm, and the ratio of the major axis to the minor axis is 1.0~3.0.

[0055] Typically, but not limitingly, the major axis of the micropore structure can be, for example, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, or 50 μm, or any value within the range of 5 to 50 μm; the minor axis can be, for example, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, or 50 μm, or any value within the range of 5 to 50 μm; the ratio of the major axis to the minor axis can be, for example, 1.0, 1.5, 2.0, 2.5, or 3.0, or any value within the range of 1.0 to 3.0.

[0056] Preferably, the cell density of the foamed light diffuser plate is 500~2000 cells / cm³. 2 This density range is conducive to the formation of a stable cell structure. A moderately distributed number of large cells can act as light channels, reducing light scattering loss and improving transmittance. Meanwhile, a high density of small cells effectively enhances the multi-directional scattering ability of light, improving haze and brightness uniformity, and mitigating display defects such as shadows and bright lines. Simultaneously, this cell density ensures sufficient structural support to maintain good mechanical strength and dimensional stability while significantly reducing the density of the board material, achieving lightweighting. This helps reduce the overall weight of large-size displays or lighting products, lowering transportation and installation costs.

[0057] Typically, but not limitingly, the cell density of the foamed light diffuser plate can be, for example, 500 cells / cm³. 2 800 pieces / cm 2 1000 pieces / cm 2 1200 pieces / cm 2 1500 pieces / cm 2 1800 pieces / cm 2 Or 2000 pieces / cm 2 It can also be 500~2000 pieces / cm 2 Any value within the range.

[0058] Furthermore, the thickness of the foamed light diffuser plate is 0.8~3.0mm.

[0059] The thickness ratio of the upper layer, the middle layer, and the lower layer is 1:(0.25~15):1.

[0060] When the intermediate layer has a large pore structure (it can have only a large pore structure, or both large and small pores can exist simultaneously), the thickness ratio of the upper layer, the intermediate layer and the lower layer is 1:(6~10):1.

[0061] Preferably, when the intermediate layer has a small-pore structure, the thickness ratio of the upper layer, the intermediate layer, and the lower layer is 1:(0.5~4):1. This thickness ratio ensures that the intermediate layer occupies the majority of the thickness, providing ample space for either large or small-pore systems. This facilitates the construction of an efficient light scattering network, maintaining high haze while forming light channels through large pores to reduce light loss and improve transmittance and brightness uniformity. The relatively thinner upper and lower layers primarily serve to smooth the surface, provide mechanical protection, weather resistance, and partially regulate light diffusion, avoiding material waste, increased density, or increased processing difficulty due to excessively thick surface layers.

[0062] The second aspect of the present invention provides a method for preparing the foamed light diffuser plate, comprising the following steps: co-extruding a three-layer structure by co-extrusion, and then drawing and cooling to form the foamed light diffuser plate.

[0063] The preparation method provided by this invention, through a multi-layer co-extrusion process combined with formulation and process control, achieves stable and continuous preparation of bimodal bubble structures in light diffusion plates. This enables precise control of optical properties, not only improving production efficiency and process tolerance but also ensuring batch-to-batch stability, making it suitable for large-scale industrial production.

[0064] Further, by weight, the formulation of the upper layer and / or the lower layer includes 80-90 parts of the first substrate resin, 0.1-1.0 parts of the light diffusing agent, 0.05-0.5 parts of the nucleating agent, 0-1.0 parts of the foaming agent, 2-5 parts of the toughening agent, 1-3 parts of the compatibilizer, 0.1-0.5 parts of the antioxidant, and 0.1-0.5 parts of the ultraviolet absorber.

[0065] Typically, but not limitingly, the formulation of the upper and / or lower layers, by weight, includes 80-90 parts of a first substrate resin (e.g., 80, 82, 84, 85, 86, 88, or 90 parts, or any value within the range of 80-90 parts), 0.1-1.0 parts of a light diffusing agent (e.g., 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0 parts, or any value within the range of 0.1-1.0 parts), and 0.05-0.5 parts of a nucleating agent (e.g., 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, or 0.5 parts, or any value within the range of 0.05-0.5 parts). The following components are used: foaming agent (0-1.0 parts, e.g., 0, 0.2, 0.4, 0.5, 0.6, 0.8, or 1.0 parts, or any value within the range of 0-1.0 parts), toughening agent (2-5 parts, e.g., 2, 3, 4, or 5 parts, or any value within the range of 2-5 parts), compatibilizer (1-3 parts, e.g., 1, 2, or 3 parts, or any value within the range of 1-3 parts), antioxidant (0.1-0.5 parts, e.g., 0.1, 0.2, 0.3, 0.4, or 0.5 parts, or any value within the range of 0.1-0.5 parts), and ultraviolet absorber (0.1-0.5 parts, e.g., 0.1, 0.2, 0.3, 0.4, or 0.5 parts, or any value within the range of 0.1-0.5 parts).

[0066] Preferably, the intermediate layer formulation comprises, by weight, 80-90 parts of the second substrate resin, 0-1.0 parts of light diffusing agent, 0.05-0.5 parts of nucleating agent, 0.4-1.0 parts of foaming agent, 2-5 parts of toughening agent, 1-3 parts of compatibilizer, 0.1-0.5 parts of antioxidant, and 0.1-0.5 parts of ultraviolet absorber.

[0067] Typically, but not limitingly, the intermediate layer formulation, by weight, comprises 80-90 parts of a second substrate resin (e.g., 80, 82, 84, 85, 86, 88, or 90 parts, or any value within the range of 80-90 parts), 0-1.0 parts of a light diffusing agent (e.g., 0, 0.2, 0.4, 0.5, 0.6, 0.8, or 1.0 parts, or any value within the range of 0-1.0 parts), 0.05-0.5 parts of a nucleating agent (e.g., 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, or 0.5 parts, or any value within the range of 0.05-0.5 parts), and 0.4-1.0 parts of a foaming agent (e.g., 0.4-1.0 parts). For example, the components can be 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, or 1.0 parts, or any value within the range of 0.4 to 1.0 parts), toughening agent 2 to 5 parts (for example, 2 parts, 3 parts, 4 parts, or 5 parts, or any value within the range of 2 to 5 parts), compatibilizer 1 to 3 parts (for example, 1 part, 2 parts, or 3 parts, or any value within the range of 1 to 3 parts), antioxidant 0.1 to 0.5 parts (for example, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, or 0.5 parts, or any value within the range of 0.1 to 0.5 parts), and ultraviolet absorber 0.1 to 0.5 parts (for example, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, or 0.5 parts, or any value within the range of 0.1 to 0.5 parts).

[0068] Preferably, the materials of the first substrate resin and / or the second substrate resin are independently PMMA, PC or PS, mainly because PMMA and PC have refractive indices of 1.49 and 1.58, respectively, which reduce interface reflection, while PS has a refractive index of 1.59, which increases interface reflection and reduces light transmittance.

[0069] Furthermore, the difference in melt flow index between the first substrate resin and the second substrate resin is ≤8.

[0070] Alternatively, when the upper layer and / or the lower layer has a small pore structure, the melt index of the first substrate resin is greater than the melt index of the second substrate resin.

[0071] Alternatively, when the upper layer and / or the lower layer has a large pore structure, the melt index of the first substrate resin is less than the melt index of the second substrate resin.

[0072] Higher melt viscosity hinders the movement of molecular chains to some extent, inhibits the growth of cells, and is beneficial for preparing small-sized cells; however, excessively high melt viscosity will inhibit the dispersion of other fillers, such as light diffusing agents, toughening agents, and antioxidants, in the matrix, which will affect light scattering to some extent.

[0073] Furthermore, the light diffusing agent includes organosilicon-based light diffusing agents.

[0074] Preferably, the nucleating agent includes silane-modified silica, which can serve as a nucleation site to inhibit the growth of pores and facilitate the preparation of small-sized pores; it can also increase the physical entanglement with the matrix molecular chain segments, thereby improving melt strength and temperature resistance; in addition, it can have a light diffusion effect, replacing some light diffusing agents.

[0075] Preferably, the silane-modified silica includes at least one of dodecyltrimethoxysilane-modified SiO2 (DTMS-SiO2), hexadecyltrimethoxysilane-modified SiO2 (HDTMS-SiO2), octadecyltrimethoxysilane-modified SiO2 (OTS-SiO2), polydimethylsiloxane-modified SiO2 (PDMS-SiO2), and polymethylsilsesquioxane-modified SiO2 (PMSQ-SiO2).

[0076] Preferably, the foaming agent has a gas generation capacity of 30~80mL / g.

[0077] Typically, but not limitingly, the gas generation capacity of the foaming agent can be, for example, 30 mL / g, 40 mL / g, 50 mL / g, 60 mL / g, 70 mL / g, or 80 mL / g, or any value in the range of 30 to 80 mL / g.

[0078] Preferably, the difference between the gas generation of the blowing agent used to form a large pore structure and the gas generation of the blowing agent used to form a small pore structure is >20 mL / g.

[0079] The difference between the gas generation of the blowing agent used to form a large pore structure and the gas generation of the blowing agent used to form a small pore structure is >20 mL / g. Typically, but not limitingly, it can be any value greater than 20 mL / g, such as 21 mL / g, 25 mL / g, 30 mL / g, 35 mL / g, 40 mL / g, 45 mL / g, 50 mL / g, etc.

[0080] Preferably, the toughening agent comprises at least one of high-impact polystyrene (HIPS), hydrogenated styrene-butadiene block copolymer (SEBS), styrene-butadiene-styrene block copolymer (SBS), and methyl methacrylate-butadiene-styrene terpolymer (MBS).

[0081] Preferably, the compatibilizer is selected from at least one of St-MMA block copolymer, maleic anhydride grafted polystyrene (PS-g-MAH), PS-SMA, SBS-g-MAH, MBS-g-MAH, and glycidyl methacrylate modified PS (PS-g-GMA).

[0082] Preferably, the antioxidant is selected from phenolic antioxidants, phosphite antioxidants, phosphorus antioxidants, or phenol-phosphorus complex antioxidants.

[0083] Preferably, the grades of the phenolic antioxidants include 1010 or 1076.

[0084] Preferably, the grade of the phosphite antioxidant includes 168.

[0085] Preferably, the grades of the phenol-phosphorus composite antioxidant include at least one of B-1, B-2, and B-3.

[0086] Preferably, the ultraviolet absorber is selected from benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, or triazine-based ultraviolet absorbers.

[0087] Preferably, the grades of the benzophenone-based ultraviolet absorbers include UV-9 and UV-531.

[0088] Preferably, the grades of the benzotriazole UV absorbers include UV-P and UV-327.

[0089] Preferably, the triazine UV absorber is designated as UV-1164.

[0090] Preferably, the formulation further includes a hindered amine light stabilizer.

[0091] Preferably, the hindered amine light stabilizer is a grade including at least one of 770, 944, 5050H or 622.

[0092] Furthermore, the co-extrusion process parameters are as follows: the temperature of each zone of the extruder is 160~280℃, the lip temperature is 210~290℃, the front, middle and rear roller temperatures are 70~130℃, and the traction speed is 2.5~3.5m / min; Alternatively, PC resin can be used as the base material, with an extrusion temperature of 200~280℃ and a lip temperature of 250~290℃.

[0093] Typical, but not limiting, co-extrusion process parameters are as follows: Extruder zone temperatures are 160~280℃ (e.g., 160℃, 180℃, 200℃, 220℃, 240℃, 260℃, or 280℃, or any value within the range of 160~280℃), lip temperature is 210~290℃ (e.g., 210℃, 230℃, 250℃, 270℃, or 290℃, or any value within the range of 210~290℃), front, middle, and rear roll temperatures are 70~130℃ (e.g., 70℃, 90℃, 100℃, 110℃, 120℃, or 130℃, or any value within the range of 70~130℃), traction... The extrusion speed is 2.5~3.5m / min (e.g., it can be 2.5m / min, 2.8m / min, 3.0m / min, 3.2m / min or 3.5m / min, or any value within the range of 2.5~3.5m / min); when PC resin is used as the base resin, the extrusion temperature is 200~280℃ (e.g., it can be 200℃, 220℃, 240℃, 260℃ or 280℃, or any value within the range of 200~280℃), and the lip temperature is 250~290℃ (e.g., it can be 250℃, 260℃, 270℃, 280℃ or 290℃, or any value within the range of 250~290℃).

[0094] A third aspect of the present invention provides the application of the aforementioned foamed light diffuser plate in a liquid crystal display.

[0095] The application provided by this invention, given the advantages of the aforementioned foamed light diffusion plate, significantly reduces the overall weight of large-size display terminals due to its lightweight characteristics, which is beneficial for transportation and installation and reduces structural support costs; it also promotes the upgrading of downstream products towards high performance, energy saving and cost reduction, and thinness.

[0096] The present invention is further illustrated below with specific embodiments and comparative examples. However, it should be understood that these embodiments are merely for illustrative purposes and should not be construed as limiting the invention in any way. Unless otherwise specified, the raw materials used in the embodiments and comparative examples of the present invention were carried out under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0097] Example 1 This embodiment provides a foamed light diffusion plate, and the specific preparation method is as follows: 1. The recipes for the upper and lower layers are as follows: GPPS (melt index: 3.5g / 10min) 95.1 portions; Nucleating agent OTS-SiO2 0.5 parts; Sodium bicarbonate (particle size 0.5-10μm) 0.5 parts; Toughening agent SEBS 1.0 part; Compatibilizer PS-g-MAH 2.0 parts; Antioxidant 10100.3 parts; Antioxidant 1680.3 parts; UV-P anti-ultraviolet agent 0.4 parts; UV-4990.2 parts; 2. The formula for the intermediate layer is: GPPS (melt index: 3.5g / 10min) 94 portions; Sodium bicarbonate (particle size 50-100μm) 0.3 parts; Toughening agent SEBS 3.0 parts; Compatibilizer PS-g-MAH 1.0 parts; Antioxidant 10100.3 parts; Antioxidant 1680.3 parts; UV-P anti-ultraviolet agent 0.4 parts; UV-4990.2 parts; 3. Mix the above-mentioned ingredients evenly to obtain the upper layer mixture, the middle layer mixture, and the lower layer mixture.

[0098] The mixture is fed into the corresponding upper / lower atomizing layer and foamed core layer feed ports of a twin-screw extruder. After being fully melted by the extruder, it is extruded from the lip, ensuring that the thickness of the upper layer: middle layer: lower layer is controlled at 1:8:1. The thickness of the light diffusion plate is 1.5T (1.5mm). The temperatures of the front, middle, and rear rollers are 85℃, 98℃, and 103℃, respectively, and the rear roller is not covered. After cooling and molding, a foamed light diffusion plate is obtained. The structural diagram is shown below. Figure 1 As shown.

[0099] Example 2 This embodiment provides a foamed light diffusion plate. The difference from Embodiment 1 is that the amount of small-pore chemical foaming agent used is 0.3 parts, and the amount of large-pore chemical foaming agent used is 0.5 parts. The other raw materials and preparation methods are the same as in Embodiment 1, and will not be repeated here.

[0100] Example 3 This embodiment provides a foamed light diffusion plate. Unlike Example 1, PMMA resin (melt flow index: 7.8 g / 10 min) is used instead of GPPS (melt flow index: 3.5 g / 10 min). One part of compatibilizer PS-MAH is added to the formulation of the upper and lower layers. The remaining raw materials and preparation methods are the same as in Example 1, and will not be described again here.

[0101] Example 4 This embodiment provides a foamed light diffusion plate. Unlike Example 1, PC resin (melt flow index: 6.5 g / 10 min) is used instead of GPPS (melt flow index: 3.5 g / 10 min), and a high-temperature microcellular foaming agent is used instead of a microcellular foaming agent. One part of compatibilizer PS-SAM is added to the formulations of the upper and lower layers, and the temperature of each zone of the extruder is increased by 40°C. The remaining raw materials and preparation methods are the same as in Example 1, and will not be repeated here.

[0102] Example 5 This embodiment provides a foamed light diffusion plate. Unlike embodiment 1, the lower layer formula does not contain a small-pore chemical foaming agent, and the lower layer structure is a solid structure. The remaining raw materials and steps are the same as in embodiment 1, and will not be repeated here.

[0103] Example 6 This embodiment provides a foamed light diffusion plate. The difference from Embodiment 1 is that PDMS-SiO2 is used to replace OTS-SiO2 in the upper and lower layer formulations. The remaining raw materials and steps are the same as in Embodiment 1, and will not be repeated here.

[0104] Example 7 This embodiment provides a foamed light diffuser plate, the structural schematic diagram of which is shown below. Figure 2 As shown, unlike Example 1, the formulations of the upper and lower layers use 0.3 parts of a large-pore chemical foaming agent, and the formulation of the middle layer uses 0.5 parts of a small-pore chemical foaming agent. The thickness of the upper layer: middle layer: lower layer is controlled at 2:1:2, and the thickness of the upper layer is 600μm. The remaining raw materials and steps are the same as in Example 1, and will not be repeated here.

[0105] Example 8 This embodiment provides a foamed light diffuser plate, the structural schematic diagram of which is shown below. Figure 3 As shown, unlike Example 1, the upper and lower layers are solid structures, no foaming agent is added to the formula, and a small-pore chemical foaming agent is added to the middle layer. The total amount of gas generated remains unchanged. The remaining raw materials and steps are the same as in Example 1, and will not be repeated here.

[0106] Comparative Example 1 This comparative example presents a foamed light diffusion board. Unlike Example 1, the upper and lower layers are solid structures, and no foaming agent is added to the formula. The remaining raw materials and steps are the same as in Example 1, and will not be repeated here.

[0107] Comparative Example 2 This comparative example presents a foamed light diffusion board. Unlike Example 1, the upper and lower layers use unmodified SiO2 directly without modifying or replacing OTS-SiO2. The remaining raw materials and steps are the same as in Example 1, and will not be repeated here.

[0108] Comparative Example 3 This comparative example provides a foamed light diffusion plate. Unlike Example 1, the middle layer is a solid structure, no foaming agent is added to the formula, and the remaining raw materials and steps are the same as in Example 1, which will not be repeated here.

[0109] Test case The performance of the foamed light diffusion plates obtained in the examples and comparative examples was tested, and the data obtained are shown in Table 1 below.

[0110] Table 1

[0111] According to the test results in Table 1, Examples 1-8 of this invention all exhibit good transmittance, haze, and brightness uniformity, with a significant improvement in shading performance. Furthermore, the density of the sheet material is reduced to approximately 25% of that of conventional products, resulting in a lighter weight. Examples 1-6 demonstrate that introducing a suitable number of small-cell structures into the upper / lower layers helps improve haze and brightness uniformity while maintaining transmittance, further reducing the shading effect of the sheet material and partially replacing the function of the diffusing agent. It was also found that when the upper and lower layer resins are PC / PMMA, it is easier to form small-sized cells. This is mainly because PC / PMMA has a stronger adsorption capacity for the foaming agent, resulting in higher solubility and more uniform dispersion of the foaming agent in the polymer, thus increasing the number of nucleation sites. Example 7 shows that increasing the thickness of the upper and lower layers and introducing a small number of large-cell structures helps improve transmittance and brightness uniformity while maintaining haze, and also avoids the rough, snowflake-like texture on the sheet surface caused by the large-cell structure. As can be seen from Example 8, the introduction of large and small pores into the foamed core layer not only reduces the density of the board to a certain extent but also increases the light diffusion angle, balancing lightweight and optical performance while improving the tolerance of the foaming process. From the comparison of the examples and comparative examples, it can be seen that the bimodal pore structure is beneficial for reducing board density, improving foaming uniformity, reducing the likelihood of bright spots, and improving the light transmittance, haze, and uniformity of the light diffusion plate. From Examples 1-8 and Comparative Example 2, it can be seen that when the nucleating agent is long-chain modified SiO2, the pores are more likely to form small-sized, low-orientation ellipsoidal structures, which to a certain extent improves the haze and uniformity of the light diffusion plate, solving problems such as severe backlight shadows.

[0112] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A foamed light diffuser plate, characterized in that, It includes an upper layer, a middle layer, and a lower layer that are stacked together, and adjacent layers have different structures; The upper layer has a large pore structure, a small pore structure, or a solid structure; The intermediate layer has a large pore structure and / or a small pore structure; The lower layer has a large pore structure, a small pore structure, or a solid structure; The upper layer and the lower layer cannot both be solid structures at the same time.

2. The foamed light diffuser plate according to claim 1, characterized in that, The large pore structure has a major axis of 150~350μm, a minor axis of 50~100μm, and a ratio of major axis to minor axis of 2.0~10.

0. Preferably, the major axis of the micropore structure is 5~50μm, the minor axis is 5~50μm, and the ratio of the major axis to the minor axis is 1.0~3.0; Preferably, the cell density of the foamed light diffuser plate is 500~2000 cells / cm³. 2 .

3. The foamed light diffuser plate according to claim 1, characterized in that, Thickness ranges from 0.8 to 3.0 mm; Preferably, the thickness ratio of the upper layer, the middle layer, and the lower layer is 1:(0.25~15):

1.

4. The foamed light diffuser plate according to claim 1, characterized in that, When the intermediate layer has a large pore structure, the thickness ratio of the upper layer, the intermediate layer and the lower layer is 1:(6~10):1; Preferably, when the intermediate layer has a small pore structure, the thickness ratio of the upper layer, the intermediate layer and the lower layer is 1:(0.5~4):

1.

5. A method for preparing a foamed light diffuser plate according to any one of claims 1 to 4, characterized in that, Includes the following steps: The foamed light diffuser plate is obtained by co-extruding a three-layer structure, followed by traction and cooling molding.

6. The preparation method according to claim 5, characterized in that, According to the weight percentages, the formulation of the upper layer and / or the lower layer includes 80-90 parts of the first substrate resin, 0.1-1.0 parts of the light diffusing agent, 0.05-0.5 parts of the nucleating agent, 0-1.0 parts of the foaming agent, 2-5 parts of the toughening agent, 1-3 parts of the compatibilizer, 0.1-0.5 parts of the antioxidant, and 0.1-0.5 parts of the ultraviolet absorber; Preferably, the intermediate layer formulation comprises, by weight, 80-90 parts of the second substrate resin, 0-1.0 parts of light diffusing agent, 0.05-0.5 parts of nucleating agent, 0.4-1.0 parts of foaming agent, 2-5 parts of toughening agent, 1-3 parts of compatibilizer, 0.1-0.5 parts of antioxidant, and 0.1-0.5 parts of ultraviolet absorber; Preferably, the materials of the first substrate resin and / or the second substrate resin are each independently PMMA, PC or PS.

7. The preparation method according to claim 6, characterized in that, The difference in melt flow index between the first substrate resin and the second substrate resin is ≤8; Alternatively, when the upper layer and / or the lower layer has a small pore structure, the melt index of the first substrate resin is greater than the melt index of the second substrate resin; Alternatively, when the upper layer and / or the lower layer has a large pore structure, the melt index of the first substrate resin is less than the melt index of the second substrate resin.

8. The preparation method according to claim 6, characterized in that, The light diffusing agent includes organosilicon-based light diffusing agents; Preferably, the nucleating agent comprises silane-modified silicon dioxide; Preferably, the silane-modified silica includes at least one of dodecyltrimethoxysilane-modified SiO2, hexadecyltrimethoxysilane-modified SiO2, octadecyltrimethoxysilane-modified SiO2, polydimethylsiloxane-modified SiO2, and polymethylsilsesquioxane-modified SiO2. Preferably, the foaming agent has a gas generation capacity of 30~80mL / g; Preferably, the difference between the gas evolution of the foaming agent used to form a large pore structure and the gas evolution of the foaming agent used to form a small pore structure is >20 mL / g; Preferably, the toughening agent comprises at least one of high-impact polystyrene, hydrogenated styrene-butadiene block copolymer, styrene-butadiene-styrene block copolymer, and methyl methacrylate-butadiene-styrene terpolymer. Preferably, the compatibilizer is selected from at least one of St-MMA block copolymer, maleic anhydride grafted polystyrene, PS-SMA, SBS-g-MAH, MBS-g-MAH, and glycidyl methacrylate modified PS; Preferably, the antioxidant is selected from phenolic antioxidants, phosphite antioxidants, phosphorus-based antioxidants, or phenol-phosphorus complex antioxidants; Preferably, the grades of the phenolic antioxidants include 1010 or 1076; Preferably, the grade of the phosphite antioxidant includes 168; Preferably, the grade of the phenol-phosphorus composite antioxidant includes at least one of B-1, B-2, and B-3; Preferably, the ultraviolet absorber is selected from benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, or triazine-based ultraviolet absorbers; Preferably, the grades of the benzophenone-based ultraviolet absorbers include UV-9 and UV-531; Preferably, the grades of the benzotriazole ultraviolet absorbers include UV-P and UV-327; Preferably, the triazine UV absorber includes the brand name UV-1164; Preferably, the formulation further includes a hindered amine light stabilizer; Preferably, the hindered amine light stabilizer is a grade including at least one of 770, 944, 5050H or 622.

9. The preparation method according to any one of claims 5 to 8, characterized in that, The co-extrusion process parameters are as follows: The temperature of each zone of the extruder is 160~280℃, the lip temperature is 210~290℃, the front, middle and rear roller temperatures are 70~130℃, and the traction speed is 2.5~3.5m / min; Alternatively, PC resin can be used as the base material, with an extrusion temperature of 200~280℃ and a lip temperature of 250~290℃.

10. The application of the foamed light diffuser plate according to any one of claims 1 to 4 in a liquid crystal display.

Images